A drive unit according to an embodiment may include: a first gear that rotates about a first axis； a second gear that rotates about a second axis extending in a direction perpendicular to the first axis； and a third gear that rotates about a third axis extending in a direction perpendicular to the first axis. Elongated elements in a shaft to operate a distal end part attached to the shaft include: a rigid first elongated element meshing with the second gear； and a rigid second elongated element meshing with the third gear. The second and third gears mesh with the first gear. The distal end part is operated in such a manner that as the first gear rotates, the first elongated element moves in a longitudinal direction of the shaft while the second elongated element moves in a direction opposite to the direction in which the first elongated element moves.
